//题目：宏#define 命令练习(2)
#include "stdio.h"
#define exchange(a,b) \
//int exchange(int a, int b)
{\   int t;\
    t=a; \
    a=b; \
    b=t; \
}
void main(void)
{
    int x=10;
    int y=20;
    printf("x=%d;y=%d\n",x,y);
    exchange(x,y);
    printf("x=%d,y=%d\n",x,y);
}